1. Field of the Invention
The present invention relates to connector assemblies and assembly methods, and in particular, to devices that are adapted for various working environments.
2. Description of Related Art
Simple, reliable and effective connectors are needed in various electronic applications. Also, avoiding transmission losses and avoiding the receipt or transmission of electromagnetic interference (EMI) is important in many applications involving instrumentation, test equipment and high frequency applications handling signals such as video signals, shortwave signals, walkie-talkie signals, etc.
The problems with losses and EMI can be ameliorated with well-known shielding techniques, which include placing critical components inside a metal enclosure, and using shielded coaxial cables and shielded connectors that have a central lead surrounded by a cylindrical metal shell (for example, BNC or TNC connectors). In particular, coaxial shielded cables that have an impedance matching that of the source and destination tend to have little EMI problems or losses due to radiation, reflections or IR losses.
Applications employing multiple connectors can be especially vulnerable or prone to losses and EMI. Known compact connectors have placed a pair of connectors in a single assembly and routed wires attached to the rear of the connectors through a 90 degree turn in order to attach to contacts designed to connect to a printed circuit board. The radius of this 90 degree turn and the geometry of nearby metallic components greatly affect the losses and EMI effects, making manufacturing difficult.
Often, such connectors are mounted through a hole in a metal panel and held in place with a nut. In these cases it is often desirable to avoid multiple ground connections to such a panel in order to avoid ground loops that can be very sensitive to low-frequency interference from power mains. On the other hand, it is highly desirable to provide a high frequency ground on the panel in the vicinity of the connector to prevent the panel from acting like an antenna for the connector. For this reason, known connectors have employed a miniature capacitive element that connects between the connector's ground and the panel. For example, the capacitive element can be pressed against the connector by a metal strap or a shielding enclosure that reaches out to make contact with the back of the metal panel.
Accordingly, minimizing losses and EMI considerations place significant burdens on the manufacturers of electronic equipment who may need flexibility in arranging and efficiently placing connectors on printed circuit boards. These considerations also place significant burdens on the manufacturers of connectors who must be able to produce high-quality connectors efficiently and to develop standardized designs that can be adapted to various environments. Connector manufacturers would also like to work with castings and molds that can meet high-performance standards when necessary but can be configured to be cost-effective for less demanding environments.
In many electronic applications requiring multiple connectors, these connectors must be color-coded to help the end-users. Stocking a large number of variously colored connectors can be inefficient for manufacturers. Also, during manufacture or repair a wrongly colored connector may be inadvertently soldered onto a circuit board, which greatly increases the time required to complete manufacturing or repair.
In FIG. 2a of U.S. Pat. No. 6,042,394 the shield of cables 18 are shown adjacent to the shields 31 around each of the center contacts 15. The specification says (column 3, lines 57–58) the cables are intended to “meet impedance requirements or to avoid deteriorating reflections,” without describing how or if the shields are connected.
In U.S. Pat. No. 6,679,728 a pair of mini BNC connectors are formed with a common metal case 10 having a connected pair of shielding cylinders 101 and 102. Casing 10 is described as having insert legs 107.
In one embodiment of U.S. Pat. No. 5,169,343 the outer contact parts of a column of coaxial connectors are connected to shielding cases 22 and 23. Also, the rear wall 33 of casing 23 serves as the shield for two separate inner contacts in the column of coaxial connectors. Each of the casings 22 and 23 have a separate pair of mounting pins 24. In the embodiment of FIGS. 6 and 7 a column of coaxial connectors has a common shield formed of a single metal block 49/50.
In U.S. Pat. No. 5,730,621 a pair of BNC or TNC connectors are mounted in parallel in a plastic block containing shunting capacitors 5 and 5′.
In U.S. Patent Application Publication No. 2003/0073328 a motherboard can be connected to a daughterboard by an interconnection system that has a number of twin lead shielded cables. Each of the signal leads of each pair is fitted with a spring contact that engages contact pads on the circuit boards. While FIG. 1A shows a relatively open structure, the cables can be packaged inside a unitary housing as shown in FIG. 13A.
In U.S. Pat. No. 6,234,834 connector bodies 21, 22 and 23 are stacked and held together with dovetails 224 and 232. Each of the connector bodies have four contacts in each of the three contact groups 3. In addition, a common ground is provided by contact 4 which has three arms 44 that are inserted between the contacts of each of the three groups 3. The stack is mounted inside a conductive shield 1. See also U.S. Pat. No. 6,508,665.
In U.S. Pat. No. 5,863,222 a pair of connectors are mounted on a common header 20, each having a number of contact pins 21. The back of both connectors is shielded by a grounded plate 30 that is connected to a circuit board by the tabs 38.
In U.S. Pat. No. 4,806,107 a high frequency backplane connector has several rows of connectors separated by elements 41, 42. The connectors are mounted in housing 50 and flexible circuit board 27 inside the housing connects these connectors to the pins 61–63 that in turn connect to a printed circuit board.
In FIG. 1A of U.S. Pat. No. 6,244,896 a row of RJ connectors are mounted inside a common shield 2 that has ground tab 15 for engaging shields of RJ plugs. In the embodiment of FIG. 4 an upper and lower row of RJ connectors are stacked together.
See also U.S. Pat. Nos. 5,190,461; 5,085,590; 5,921,814; 6,626,700; and 6,022,245.